I was asking someone very knowledgeable in the area
of epoxy systems about gas tank sealants for
composite tanks that can stand up to mogas.

I'm just wondering how being very knowledgeable in the area of epoxy systems
relates to being knowledgeable about the properties and behavior of
gasoline.  ??
I don't find the smell of auto gas any more unpleasant than that of 100LL, I
don't plan on having any in the cabin with the passengers, and I frequently
go more than a month between fill-ups on my XJS, and performance is never an
issue.

I do think that if left for long periods, maybe like 6 months to a year, it
can cause some 'gumming' problems in a carburetor, and if not in a sealed
container, loses some of the more highly volatile fractions, which could
change the properties.

It has also been shown that alcohol or ethanol in auto gas can result in the
softening of the surface of EZ-poxy over a period of years.

 But then I (also) am not an expert on the properties and behavior of auto
fuel.

Al